Method of removing metal cores



Jan. 17, 1928. 1,656,312

c. D. BLACK METHOD 0F REMOVING METAL CORES Filed Sept. 24, 1924 2 Sheets-Sheet 1 lll/IIIA Jan. 17,1928. 1,656,312

C. D. BLACK E I m Patented Jan, 17, 1928.`

UNITED STATES PATENT OFFICE.l

examen.

BLACK, I yAKRON', 0R10, SIGNOR TO m B. l. GOODBICH nm, i

0l' NEW YORK, Il'. Y., A GOBPOBATION 0F NEW YORK.

muon or momo man com Anuman am september u, im. anni l. mp7s.-

This invention relates to molding and forming operations and more particularly to a means for molding under heat and pres.

' sure, or under pressure alone, hollow bodies irrespective of their conti ration and removing from the hollow bo ies the cores empliged in the molding rocess.

principal object o my ,invention is to provide an improved method for removing 1o the metal cores emlloyed in the formation of y hollow bodies by e fusion of the metal of the cores without detriment to the formed bodies. A further object of my invention is to rovide an improved method for the pro uction of sound projectors from hard rubber and for removing the cores employed in the molding operation.

In the manufacture of hard-rubber sound projectors, and similar hollow articles which normally have `relatively thin walls, it is desirable to employ forming cores. and to apply pressure to the walls of the article during the molding process. In some cases, the cores, by reason of the shape of the neck of the projectors, cannot beremoved therefrom as a unit after the vulcanization process. l

It has been heretofore ro osed to make 4such a neck forming core ol ow and a fusible metal, and to melt out the fusible core after vulcanization'b passin therethrough a heated medium. Iii accor ance with the present invention, a fusible core of this character is removed from a sound projector 85 by placing the core containing portioii of the projector in a high frequency induction furnace and melting out the core.

In the accompanying drawings, Fi 1 is a view in vertical section of a soun proj ector disposed in a high frequency induction furnace and illustrating an embod1ment of m invention; Fig. 2 is a view in elevation ofy the inductor unit of Fig. 1; Fig. 3 is a view partially iii side elevation and partially l4&5 in vertical section of a modified embodiment of the construction of Fig. 1; Fig. '4 isa view partially' inelevation and partially in section of the structure illustrated in Fig. 3.

. Referring more particularly to the drawings, I show in Figs. 1 and 2 a high fre- 50 quency linduction furnace 10, consisting of a thin-walled hollow cylinder 11 of electrical insulating material, such as quartz, micanite or asbestos, an inductor 12 in the form of a helicall coiled bar surrounding the cylinder 11, an brackets 13 of electrical insulatinr material for supportin the cylinderll and the inductor 12 in fixe relation to a frame or table 14 upon which the 'furnace is mounted. i

As shown, the axis of the linder 11 is oblique to its bases and the coils of the inductor are in general arallelism to the bases, the arrangement o the furnace being particularly adapted for receiving the goose- Il neck of the projector and causing the induced electric currents to be set up in the core of a projector of they special shape illustrated.

The table 14 is provided with a top 16 hav- 70'- ing an openin 17 therein to receive and suport the soun projector 18, the construction eing such that the neck of the projector 19 containing the metallic core 20 is entirely within the inductor coil 12. It is to be understood that the core section within the bell or flarin` mouth portion of the projector during te molding operation is `fithdrawn before placing the pro'ector in the furnace, as hereinafter describe A catch basin 23 is supported on the shelf `24 of the frame 14 in such position as to receive the fused metal of the core 20. If desired, an electric resistance 25 may be disposed around the basin 23 to maintain the 85 metal in a molten condition and ermit it to be withdrawn through the va ve 26 and spout 27.

Unvulcanized rubber in the f orm of sheets of suitable thickness Vis fitted about a core, which is preferably made in two sections, a bell section for the large fiarin end, which core section may be of any suita le material, and a neck section 20 of low temperature fusing metal. The rubber covered core sec- 05 tions are then encased in a suitable mold,

for example of the two-section t rubber subjected to pressure. projector is then vulcanized b the application of heat, either in the mol or, the mold being removed, in open dry heat on the core. Upon cooling, the bell section of the core is removed from the vulcanized article and the core 20, which is held in the sinuous passage of the sound projector, is removed by placing the projector in the induction furnace in the manner shown in Fig. 1. A high fre uency current is then passed through the in uctor coil 12 and the core being within the field of the inductor is heated to a meltin temperature by direct induction, the ed y currents which cause the heating being developed directly in the core. The metal upon melting is drained into the catch basin 23. With electric currents having frequencies of the order of from 10,000 to 20,000 cycles per e, and the e molded second and potentials of the order of from 6,000 to 10,000 volts, a few minutes suilices entirely to fuse a hollow core of low melting point metal. e

In the modification illustrated in Figs. 3 and 4, two inductors 30 and 31, each of annular conformation and comprising spirally wound bars, are spaced sutliciently apart to receive between them one or more sound projectors, two sound projectors being illustrated, referably su ported with the lar e end or ell downward y to permit partial y fused portions of the core to fall bodily out of the sound projector, should they become loosened sufficiently therein.

The furnace units of the a paratus of Figs. 3 and 4 are similar to t at already described in connection with Fig. 1. Electrical insulating disks 32 lie contiguous to the induction coils 30 and 31 and internally thereof. Brackets 33 of electrical insulating material are secured to a table 34 and serve to suiport both the inductors 30 and 31 and the isks 32 in proper position. Pins 35 projecting from arms 36, also secured to the table, and lugs 37 on the table 34 are rovided to hold the sound projectors in inverted upright position during the fusing of the cores 20. The fusing metal of the cores is cau ht in suitable rece tacles disposed beneat the openings 39 in the table 34. The apparatus of this embodiment o crates in all respects similar to that of ig. 1 described above and further exposition thereof is here deemed to be unneceshile this invention has been disclosed in f connection with the manufacture of hard rubber sound rojectors, it is obvious that it may be emp oyed for the wide variety of molded or ormed articles. The present invention also contemplates the separation of metals having) different fusing temperatures which have een cast one to the other or plated one upon the other, as

production of a for example, the removal of Babbitt metal from a bearing, or the production of hollow metal articles of irregular shape by metal plating a core of low fusing temperature, and then removing said core by fusing in an induction furnace.

This invention has many advantages when applied to the arts as above suggested, chief o which are the simplicity o the method, its low cost of operation and maintenance, and the comparative freedom of hazard to the o erator carrying out the process.

I c aim:

1. The method of .producing hollow, vulcanized rubber articles which comprises forming unvulcanized rubber about a core of low fusing point, vulcanizing the rubber on the core, and thereafter lacing the article with its core d' se in the space between the windin o an induction heater, and passing throug the windings of such heater an alternating electric current having a frequency of the order of from 10,000 to 20,000 cycles er second.

2. The metho of produci ed articles which comprises orming plastic material about a core of metal havin a relatively low fusing point, hardening tie plastic material about the core to form a selfsustaining construction, thereafter melti out the metal of the core by setting up therein eddy currents induced rom an induction coil carrying a high frequency alternating current.

3. The method of producin hollow vulcanized hard-rubber articles w ich comprise forming an unvulcanized hard-rubber composition about a core of relatively low fusing point, vulcanizing the rubber on the core to form a self-sustamin construction, and thereafter melting out t e material of the core bg setting up therein edd currents induce from a coil traversed gy a high frequency alternating electric curren 4. The method of producing hollow, vulcanized rubber articles which comprises forming a vulcanizable rubber composition about a core of low fusing point, vulcanizing the rubber on the core at a temperature lower than the fusing point of said core and thereafter melting out the material of the core b setting up therein eddy currents induce from a coil traversed by a highfrequency alternating electric curren 5. The method of producing hollow, vulcanized rubber articles which comprises orming a vulcanizable rubber composition about a relatively thin hollow core having a fusing point somewhat in excess `of the temperature of vulcanization of the rubber composition, vulcanizin the rubber on the core, and thereafter me ting out the core by setting up therein eddy currents induced by an in uction heater traversed by high-frequency alternating electric currents.

hollow, mold- 6. The method of producing hollow, vulcanized rubber articles which comprises forming a, vulcanizable rubber composition about a metal core having a higher fusing point than the vulcanizing temperature of said composition, vulcanizing the rubber on thecore at a lower temperature than that of the fusing point of the core, cooling the vulcanized rubber article, and thereafter melting out the metal of the core by setting up therein eddy currents induced from a coil traversed by high-frequency alternating electric currents.

In Witness whereof I have hereunto set my hand this 17th da of September, 1924.

' CHAllLES D. BLACK. 

